The invention relates to compounds, methods and kits for the determination of immunosuppressant drugs, in samples, such as patient samples, known or suspected to contain one or more of such immunosuppressant drugs.
The body relies upon a complex immune response system to distinguish self from non-self. At times, the body's immune system must be controlled in order to either augment a deficient response or suppress an excessive response. For example, when organs such as kidney, heart, heart-lung, bone marrow and liver are transplanted in humans, the body will often reject the transplanted tissue by a process referred to as allograft rejection.
In treating allograft rejection, the immune system is frequently suppressed in a controlled manner with drug therapy. Immunosuppressant drugs are therapeutic drugs that are carefully administered to transplant recipients in order to help prevent allograft rejection of non-self tissue. Immunosuppressive drugs can be classified as follows: glucocorticoids, cytostatics, antibodies, drugs acting on immunophilins, and other drugs such as interferons, opiates INF binding proteins, mycophenolate, FTY720 and the like. A particular class of immunosuppressant drugs comprises those drugs that act on immunophilins. Immunophilins are an example of high-affinity, specific binding proteins having physiological significance. Two distinct families of immunophilins are presently known: cyclophilins and macrophilins, the latter of which specifically bind, for example, tacrolimus or sirolimus.
Two most commonly administered immunosuppressive drugs to prevent organ rejection in transplant patients are Cyclosporine (CSA) and FK-506 (FK or tacrolimus). Another drug that finds use as an immunosuppressant in the United States and other countries is sirolimus, also known as rapamycin. Derivatives of sirolimus are also useful as immunosuppressants. Such derivatives include, for example, Everolimus, and the like.
The side effects associated with some immunosuppressant drugs can be controlled in part by carefully controlling the level of the drug present in a patient. Therapeutic monitoring of concentrations of immunosuppressant drugs and related drugs in blood is required to optimize dosing regimes to ensure maximal immunosuppression with minimal toxicity. Although immunosuppressant drugs are highly effective immunosuppressive agents, their use must be carefully managed because the effective dose range is often narrow and excessive dosage can result in serious side effects. On the other hand, too little dosage of an immunosuppressant can lead to tissue rejection. Because distribution and metabolism of an immunosuppressant drug can vary greatly between patients and because of a wide range and severity of adverse reactions, accurate monitoring of the drug level is essential.
There is, therefore, a continuing need to develop fast and accurate diagnostic methods to measure levels of immunosuppressant drugs or derivatives thereof in patients. The methods should be capable of being fully automated and should selectively detect the parent drug while minimizing inaccuracies resulting from the cross-reactivity of its metabolites or from constituents in a sample suspected of containing the immunosuppressant drug.